Inkjet Recording Device Reducing Coulomb Repulsion via Block Scanning

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Solution Overview

Problem

Inkjet recording devices face printing distortion and reduced printing speed due to Coulomb repulsive forces between ink particles, especially when printing complex characters with high information density, as existing methods rely on inserting uncharged particles to manage these forces.

Innovation Solution

The inkjet recording device divides the dot pattern of each character column into blocks and alternates the order of ejecting ink particles in block units, applying a charging voltage to increase the distance between charged particles, thereby reducing Coulomb repulsive forces and maintaining high printing quality without relying on uncharged particles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If ink particles are ejected sequentially from lower dot position to upper dot position (forward scanning), then printing can be performed efficiently, but the narrow interval between adjacent ink particles increases Coulomb repulsive force causing printing distortion

Engineering Contradiction:

Improveprinting efficiencyVSAvoidprinting position accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent inverts the conventional forward scanning sequence by ejecting ink particles in reverse order (from upper dot position to lower dot position) or using alternating scan directions. This inversion changes the temporal sequence of particle ejection, increasing the time interval between consecutive charged particles and reducing Coulomb repulsion effects while maintaining printing efficiency

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent implements periodic action by alternating the scanning direction between upward and downward movements between lines. This periodic reversal creates regular intervals in particle ejection timing, allowing Coulomb forces to dissipate between successive charged particles while maintaining continuous printing operation

Inventive Principle:

Principle #19Periodic action

2Manufacturing precision

If uncharged ink particles are inserted between charged ink particles to reduce Coulomb repulsive force, then printing quality improves, but printing speed decreases to 1/n times

Engineering Contradiction:

Improveprinting qualityVSAvoidprinting speed

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent extracts and eliminates the unnecessary uncharged ink particles from the ejection sequence. By removing these non-contributing particles while maintaining adequate time intervals between charged particles through optimized scanning control, the system achieves both high printing quality and maintained printing speed

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent ensures continuous ejection of only the necessary charged ink particles without interruption by uncharged particles. The scanning control maintains continuous useful action by optimizing the timing and sequence of charged particle ejection, eliminating wasted ejection cycles while preserving print quality

Inventive Principle:

Principle #20Continuity of useful action

3Quantity of substance

If dots are continuously charged in vertical columns for complex characters with large information density, then printing capacity increases, but Coulomb repulsive force causes severe printing distortion

Engineering Contradiction:

Improveinformation densityVSAvoidprinting distortion

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent segments the continuous vertical column of charged particles into discrete groups or lines with alternating scan directions. This segmentation breaks up the continuous charge sequence, creating natural intervals between charged particles that reduce cumulative Coulomb repulsion while maintaining the ability to print complex high-density characters

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for high-quality printing with reduced printing distortion and maintained speed, even when printing complex characters with large information density, by enlarging the spatial distance between charged ink particles and minimizing the influence of Coulomb forces.

Implementation Method 1

the narrower an interval between the ink particles is, the further a Coulomb repulsive force generated between the ink particles increases

Methodology Applied

Scientific EffectCoulomb repulsive force: Coulomb's Law

Implementation Method 2

the charged ink particles are deflected by a deflection electrode

Methodology Applied

Scientific EffectElectrostatic deflection: Lorentz Force

Data Source

PatentUS11376848B2Inkjet recording device and control method for inkjet recording device

Publication Date: 2022.07.05 HITACHI IND EQUIP SYST CO LTD

AI summary

To realize high-quality printing with less printing distortion by reducing an influence of a Coulomb force that acts between ink particles which are ejected in an inkjet recording device.The inkjet recording device is configured to charge ink particles ejected from a nozzle, deflect the charged ink particles, and print a character in a shape of an object to be printed. In the inkjet recording device, dots of each column of the character to be printed are divided into a plurality of blocks in a column direction. In addition, charging voltage data in which the order of the ink particles corresponding to the dots is switched in the divided block unit is stored, and a predetermined charging voltage is applied to the charging electrode on the basis of the charging voltage data.